Emergency Instructions:220 V DC Failure

220 V DC Failure

Unit condition

Ø  DCDB section-1 & 2 under voltage alarm in LVS-5

Ø  All HT/LT Breakers Indication Becomes Bad

Ø  Boiler will Trip on MFT ( after 2 Sec)

Ø  Turbine will Trip on MFT

Ø  Generator will not Trip as GCB Protection will not act

Ø  Generator will run as Synchronous Motor

Ø  HP/IP/LP Casing Exhaust Temperature will start increasing

Ø  400 KV Breakers can be Operable

Ø  Feeders of Mill will Trip on MFT

Ø  Fans(ID, FD, PA), Mills, BCW Pumps etc will continue to run

Ø  DC Drives can not come in service

Actions

Ø  Sequence to Trip Drives:

·         PA fan

·         Mills

·         One set ID/FD

·         Another set of ID/FD

·         BCW Pumps

·         MDFP

·         CEP

·         SG ECW

·         TG ECW

·         Air compressors

·         CW Pumps

Ø  Start DG set

Ø  Start AOP-1, SOP-1, AOP-1 of TDBFPs, PW-1

Ø  Trip Normal Incomer breaker from unit service Board to Emergency board from Switchgear

Ø  Close DG set incomer breaker to emergency Board from Switchgear

Ø  Start AOP-2, SOP-2, AOP-2 of TDBFPs, PW-2

Ø  Trip 400 KV Main/Tie GCB from CCR/Switchyard

Ø  Trip Station Transformer after shifting critical equipments

Ø  This will result in Total Power Failure with Emergency Board in charged condition